How can you direct a sound at a certain area and how does it work?

Question

i think its called acoustic beaming

Answer 1

Using some kind of parabolic speaker.

http://www.museumtools.com/secretsound.html
http://www.northernsound.net/Sales/speakers/meyersound/industrial.html

Answer 2

A sound, as you know, is a wave that propagates in a medium.
Horns and pipes serve that purpose well.
The sound wave would bounce off the boundaries of these pipes and can propagate a considerable distance. That phenomenon accentually was used early in acoustic telephones used between rooms and on large ships.

Horns work by focusing the propagation of a sound wave in a specific direction. Parabolic speakers allow reflection of a sound wave from the focal point of the parabolic shape and a wave reflects from a surface and propagates in a beam.

Answer 3

The frequency of a sound wave is measured in hertz and it has been found that If the sound waves are disrupted with ultrasonic air waves of about 100,000 hertz, they can be forced not to spread out and focused to travel in a chosen direction. The sound is beamed in one direction ie. acoustic beaming.

Hyper Sonic Sound
"when two tones are played simultaneously and loudly enough, they interact to spawn two new tones. One carries a frequency that is the sum of the two starting frequencies; the other is their difference. So if you blast inaudible ultrasonic frequencies of 100 kilohertz and 101 kilohertz, you get an inaudible 201 kilohertz overtone plus an undertone of 1 kilohertz that is well inside the range of hearing. And since ultrasound travels in a tight line akin to laser light, the emergent tones are audible only in a narrow, cylindrical path from source to ear."

Answer 4

I'm not sure how you intend to use this, but if you use sound as a weapon (see link) the effects can be devastating. I believe the military have experimented with it's use at both animate and inanimate objects. Tread carefully with this subject.